1. Openings in engine cylinder blocks for exhaust and intake valves and water connections. Also see adjustable variable exhaust port , exhaust port , intake port , transfer port , and valve port .
2. To smooth out, align, and somewhat enlarge the intake passageway to the valves or intake chambers (especially in two-stroke engines).
3. A small hole in the master brake cylinder to permit fluid to return to the reservoir. See compensating port and intake port .